Christopher E. Kuklewicz

Generation of ultrabright tunable polarization entanglement without spatial, spectral, or temporal constraints

The need for spatial and spectral filtering in the generation of polarization entanglement is eliminated by combining two coherently driven type-II spontaneous parametric down-converters. The resulting ultrabright source emits photon pairs that are polarization entangled over the entire spatial cone and spectrum of emission. We detect a flux of ,12 000 polarization-entangled pairs/s per mW of pump power at 90% quantuminterference visibility, and the source can be temperature tuned for 5 nm around frequency degeneracy. The output state is actively controlled by precisely adjusting the relative phase of the two coherent pumps.

High-flux source of polarization-entangled photons from a periodically poled KTiOPO~4 parametric down-converter (5 pages)

We have demonstrated a high-flux source of polarization-entangled photons using a type-II phase-matched periodically poled KTiOPO{sub 4} parametric down-converter in a collinearly propagating configuration. We have observed quantum interference between the single-beam down-converted photons with a visibility of 99% together with a measured coincidence flux of 300 s{sup -1}/mW of pump. The Clauser-Horne-Shimony-Holt version of Bells inequality was violated with a value of 2.711{+-}0.017.

Time-bin-modulated biphotons from cavity-enhanced down-conversion.

We have generated a new type of biphoton state by cavity-enhanced down-conversion in a type-II phase-matched, periodically poled KTiOPO4 crystal. By introducing a weak intracavity birefringence, we obtained signal and idler photons whose quantum interference was modulated between singlet and triplet signatures according to their arrival-time difference. This cavity-enhanced biphoton source is spectrally bright, yielding a single-mode fiber-coupled coincidence rate of 0.7 pairs/s per mW of pump power per MHz of down-conversion bandwidth.

Source of polarization entanglement in a single periodically poled KTiOPO4 crystal with overlapping emission cones.

We present a simple polarization entanglemenet source based on type-II phase-matched parametric down-conversion in periodically poled KTiOPO4. By use of noncritical phase matching in a noncollinear geometry the single-crystal source emits a cone of polarization-entangled photons. Two beams on opposite sides of the cone are selected for measurements to yield an observed flux of 820 pairs/s per mW of pump power with a two-photon fringe visibility of 96%. With this source we measure a violation of Bells inequality of 140 standard deviations in 160 s.

Ultrabright tunable photon-pair source with total-flux polarization-entanglement

We demonstrate a continuous-wave dual-pump tunable source of polarization-entangled photons that requires no spectral or spatial filtering and emits ten times more pairs per mW of pump than pervious sources.

High-flux entanglement sources using periodically-poled nonlinear crystals

We have efficiently generated colinearly-propagrating entangled photon pairs from nondegenerate type-I and degenerate type-II quasi-phase matched parametric downconverters based on periodically-poled lithium niobate and potassium titanyl phosphate, respectively.

Novel time-bin dependent polarization entanglement via cavity-phase control

We have produced spectrally-bright polarization-entangled biphotons using a cavity-enhanced type-II PPKTP parametric downconverter. By detuning the cavity birefringence we have generated a novel time-bin dependent polarization-entangled biphoton state.

Generation of polarization entanglement from a PPKTP parametric downconverter

We have generated polarization-entangled photon pairs from a type-II phase-matched periodically poled KTP parametric downconverter with collinear outputs. Bells inequality was violated with a value of 2.57 /spl plusmn/ 0.03.